1. Field of the Invention
The present invention generally relates to robotics and, more specifically, to systems for coupling and decoupling tools from robotic hands.
2. Description of the Prior Art
Robots are widely used in the field of automated manufacturing and material handling. Pursuant to such uses, there exists a need for robots to grasp various objects and tools. For example, when assembling circuit boards in automated operations, it is highly desirable that a robotic hand be able to sequentially grasp a first tool, then a second tool, and so forth. As another example, in automated laboratory operations, it is desirable that a robot be able to exchange tools which are adapted to specific tasks, such as for retrieving articles from centrifuges or for operating devices such as syringes.
The ability of a robot to interchangeably use a number of different tools can be referred to as "tool interchangeability". Generally speaking, the benefit of tool interchangeability are that a single robot can be used flexibly and that the need for multiple robots is minimized. Although it is known to provide mechanisms that provide robots with the ability to exchange tools without human assistance, such mechanisms have had drawbacks including complexity and cost. One example of an interchanging mechanism is set forth in U.S. Pat. No. 4,676,142, entitled "Adapter With Modular Components for a Robot End-of-Arm Interchangeable Tooling System."
The difficulties in designing mechanisms that provide robots with the ability to exchange tools can be appreciated by contrasting the capabilities of human hands with the capabilities of typical robotic systems. For example, a human worker can usually easily pick up a dropped tool; by way of contrast, even a robotic system that is equipped with machine vision often cannot identify a dropped tool, let alone retrieve it. Thus, in designing systems that provide tool interchangeability for robots, attention must be paid to features that prevent dropping of tools. Specifically, systems must be designed to provide tool mechanisms that reliably lock interchangable tools to robotic hands so that the tools will not normally unlatch while working but can be readily coupled and decoupled when interchanging tools.
Further, it can be appreciated that the risks of a robot inadvertently dropping a tool are greatest when a robotic hand attempts to grasp a tool (as during tool coupling) and when a robotic hand attempts to exchange tools (or during tool decoupling). In other words, the risks of dropped tools are greatest just before, or just after, a robotic hand latches to a tool. During such periods, errors in positioning the robotic hand can cause a tool to be inadvertently dropped.
The above-described difficulties in designing mechanisms that provide robots with capability to easily and reliably interchange tools are especially acute when the tools are small. Small-scale tools are required, for example, when circuit packages of the surface mounted type are assembled onto printed circuit boards. Also, small tools are often required when a robotic hand is to operate in a chemical or biology laboratory.